This invention relates to ranging drum shearers and in particular to double ended shearers in which the cutter drums are each driven by a transverse electric motor mounted on the respective ranging arm.
Ranging arm shearers are track mounted and run along the track in both directions. The track incorporates a conveyor to carry the cut coal and that conveyor runs in only one direction according to the layout of the mine.
When the shearer is running in the same direction as the conveyor the cut coal falls into the conveyor ahead of the machine, but when the shearer is running against the run of the conveyor, the cut coal passes under the machine body. Consequently a low powered lump breaker, or `coal sizer` is mounted across the relevant end of the machine to reduce large lumps of coal to a size sufficient to pass under the machine body.
A problem which arises with electric drum-drive shearers is how best to mount a coal sizer and its associated transvers electric motor across the end face of the machine body.
One known arrangement provides an arm extending longitudinally of the goaf side of the machine and carrying the coal sizer and electric motor at its outer end. A disadvantage of such an arrangement is that the arm lies alongside the electric motor which drives the drum of that ranging arm, so if that motor requires to be removed, the coal sizer arm together with the coal sizer and its electric motor must first be removed and later replaced. As the arm has to carry the coal sizer and its electric motor, it is a relatively heavy member and its removal and replacement with the coal sizer and motor still attached is labour intensive or requires the use of lifting apparatus.
An object of this invention is to provide a coal sizer mounting which obviates or mitigates the aforementioned problem.
According to one aspect of the present invention there is provided a ranging drum shearer wherein the or each cutter drum is driven by a transverse electric motor mounted on the or each ranging arm, the or each electric motor being contained in a cylindrical shroud, a coal sizer pivotally mounted on a shroud and disposed at a selected height above a datum, and means to retain the coal sizer in said disposition when the associated ranging arm is pivotally raised or lowered.
According to another aspect of the present invention there is provided a ranging drum shearer in which a ranging arm is pivotally mounted on at least one end of the body of the shearer and carries a cutter drum, the or each arm having an associated transversely mounted electric motor which drives the cutter drum of said arm, said electric motor being contained within a transversely disposed cylindrical shroud mounted on or integral with the ranging arm and spaced longitudinally of the axis of rotation of the ranging arm, a coal sizer and an associated transversely mounted electric motor spaced from an end face of the body and having mounting means to engage the adjacent shroud for rotational movement relative thereto about the axis of the shroud, and means to maintain constant the disposition of the coal sizer in use relative to a conveyor below the body of the shearer when the ranging arm is raised or lowered.
Preferably, said means to maintain constant the disposition of the coal sizer relative to the conveyor comprises an arm longitudinally disposed and pivotally mounted at one end on the axis of the ranging arm, a keyway in said arm containing a key on the axis of the coal sizer to provide for longitudinal movement of the coal sizer relative to the body of the shearer whereby on pivotal movement of the ranging arm and corresponding movement of the shroud, said arm remains stationary and The distance between the key and the transverse axis of the shroud is maintained by longitudinal adjustment of the coal sizer in the keyway,
Preferably also, the coal size position-control arm is retained stationary by means of a hydraulic ram which can also be used to alter the disposition of the arm and thus the height-setting of the coal sizer and to cushion the shock loading on the coal sizer during use.